Apparatus for burner ignition and flame detection



Oct. 3, 1961 R. E. SCHRETER APPARATUS FOR BURNER IGNITION AND FLAME DETECTION e SheeIs-Sheet 1 Filed Oct. 17, 1958 I I fig u Q r M m w w M 3) a w m M n M J J N FM 1 a W g. m i 4 w -r|:\\ 11 w K n i lmm u M 0 M rW II IIII I; m I T F 5 .1 W III. M

a /u\ p M I; r 5 Mg H mm M IIL J A M w i M W01 INVENTOR. 205587 E. SCHEETE/Z Oct. 3, 1961 R. E. SCHRETER 3,

APPARATUS FOR BURNER IGNITION AND FLAME DETECTION Filed 001:. 17, 1958 e Sheets-Sheet 2 4 INVENTOR. 205527 E- SCHEETEE ,4 T7'02/VEYS APPARATUS FOR BURNER IGNITION AND FLAME DETECTION Filed Oct. 17, 1958 GSheets-Sheet 3 llh J H 5 /8 2, 119m; 26 I W azzzrro/Pam/f E INVENTOR.

E I 205527 E. 50/215752 15*. BY

Oct. 3, 1961 R. E. SCHRETER 3,002,550

APPARATUS FOR BURNER IGNITION AND FLAME DETECTION Filed 001;. 17, 1958 6 Sheets-Sheet 4 INVENTOR. 5537 5 SCHPET Oct. 3, 1961 R. E. SCHRETER APPARATUS FOR BURNER IGNITION AND FLAME DETECTION Filed Oct. 17, 1958 IN VEN TOR. E. SC/1 257252 ,4 7 GENE/5 6 Sheets-Sheet 5 N 1* g} R w 3 I T 05527 BY J M Q Q I Oct. 3, 1961 R. E. SCHRETER 3,002,550

APPARATUS FOR BURNER IGNITION AND FLAME DETECTION I N V EN TOR. E0552 7 E. 50/257152 n Buzwzz 3,002,550 APPARATUS FUR BURNER IGNITION AND FLAll E DETECTION Robert E. Schreter, Forest Hills, N.Y., assignor to Hauclr Manufacturing Co., Brooklyn, NY, a corporation of New York Filed Oct. 17, 1958, Ser. No. 767,984 24 Claims. (Cl. 158-48) This invention relates to fuel burners and more particularly to apparatus for burner ignition and flame detection.

In the event of flame failure there is danger because of continued supply of fuel. In large installations flame detection devices are used to operate an alarm, or shut off the fuel supply, or preferably both. Common types of flame detection means employ a flame sensing pickup in the form of an electrode immersed in the flame, and depend on ionization of gas molecules during combustion. Some respond to the rectification of an alternating current as between a small electrode and a larger surface, and some respond to a change in conductivity. Fuel burners also have an electrode (or sometimes two) for spark ignition.

The primary object of the present invention is to com bine ignition and flame detection apparatus so that the same electrode may he used for both. This is sometimes of great importance because of difliculty in gaining access to the flame region and mounting an electrode thereat. For example, in the case of radiant burners using a large heated refractory block, it is necessary to gain entry through the body of the block.

A further object of the present invention is to provide apparatus with a timer (e.g. a time delay relay) measuring a safe interval during which ign tion should occur when starting the burner. This has advantages such as shutting off the apparatus in the event the operator holds his control means too long at the start position, or if the switch jams and remains in the start position.

A further object of the invention is to devise apparatus which may be used with burners having either a single or a pair of ignition electrodes, or with either gas or oil fuel.

Still another object of the invention is to make it ap plicable to either a single burner, when no pilot flame is provided, or to the pilot burner when a pilot flame is used, and in the latter case, to appropriately control the main as well as the pilot fuel supplies.

Still another object is to provide apparatus for simultaneous control of multiple burners. In one form a single high voltage source is used with a distributor and a multiple high voltage switching means, and in another form low voltage wiring may run to the different burners for the control of multiple high voltage sources and high voltage relays localized at the burners.

To accomplish the foregoing general objects, and other more specific objects which will hereinafter appear, my

invention resides in the burner ignition and flame detec tion elements and their relation one to another, as are hereinafter more particularly described in the following specification. The specification is accompanied by drawings in which:

FIG. 1 is a wiring diagram explanatory of one form of my invention;

FIG. 2 is a similar diagram showing another form of the invention in which a timer is used;

FIG. 3 is a wiring diagram for another form of the invention much like that shown in FIG. 1, except that a transformer having dual secondaries is employed for ignition across a pair of electrodes;

FIG. 4 is a wiring diagram for still another form of 3,002,550 Patented Oct. 3, 1961 the invention which resembles that shown in FIG. 3, but with the addition of a timer;

FIG. 5 is a wiring diagram showing the invention applied to a burner having a pilot flame;

FIG. 6 is a wiring diagram for still another form of the invention similar to that shown in FIG. 5 but with the addition of a timer;

FIG. 7 is an end view of a manually operated control means or switching device embodying features of my invention;

FIG. 8 is a side elevation of the same, simplified by the omission of electrical rotor and stator detail;

FIG. 9 is a section taken approximately on the line 9-9 of FIG. 8;

FIG. 10 is a section taken approximately on the line 1tllll of FIG. 8, and shows some of the rotor and stator detail;

FIG. 11 shows a burner having a dual-purpose electrode;

FIG. 12 is a schematic section through a radiant refractory burner, and is explanatory of an advantage of the invention;

FIG. 13 is a wiring diagram showing my improvement applied to a multiple burner installation, with high voltage wiring extending from the control means to the different remote burners; and

FIG. 14 is a wiring diagram showing my improvement applied to a multiple burner installation with low voltage wiring extending from the control means to the difierent remote burners.

Referring to the drawing, and more particularly to FIGS. 1 and 11, the apparatus is applied to a fuel burner generally designated 12 having an electrode rod 14, the tip of which is disposed near another conductive metal part of the burner. Referring to FIG. 11, the latter metal part is shown at 422. The particular burner here illustrated is a pilot burner rather than a main burner, and that is where the invention is most usually used, but for simplicity of explanation the diagram of FIG. 1 first shows the invention as applied to a single burner. In FIG. 11 the pilot burner is a gas burner, and the premixed air and gas fuel is supplied by a pipe 418 to the burner body 42%. The nozzle is shown at 422. The electrode 14 is supported in insulation material shown at 424, and provision for connection of a high voltage conductor is made at 426, at the upper end of the electrode 14. Gas from body 420 flows around the electrode and also through passages 423. Auxiliary combustion air holes may be provided at 439, if desired.

In a conventional pilot burner the electrode 14 terminates ilush with the part 416, or it may project slightly, say V inch. It is used solely as an ignition electrode. For my purpose the electrode is preferably lengthened, and in the present case projects one-quarter inch beyond the part are. This lengthened electrode acts not only for ignition when starting, but also as a flame sensing pickup for the flame monitoring circuitry during operation of the burner.

Reverting now to the diagram of FIG. 1, the apparatus comprises a high voltage source 16, in this case a step-up transformer, to cause an ignition spark between the electrode 14 and the burner 1.2.. The output voltage may he say 6000 for gas, and 12,009 for oil. The apparatus further comprises a flame detection or monitoring unit generally designated 18 which is responsive to the presence of flame immersing the electrode. More specifically, it may be responsive to the rectifying action which takes place when an alternating current is applied between an electrode 14 of small area and another electrode of large area, in this case the burner, or it may be responsive to the change in conductivity caused by the presence or absence of flame.

The apparatus further comprises a switching means 20, and circuitry so connecting the electrode 14, the source 16,. and the flame detection unit 18, with said switching means 20, that the said switching means may be used to connect the electrode 14 to either the source 16 for starting the burner, or to the detection unit 18 for running of the burner. When starting, the switching means handles a high voltage and therefore requires high voltage construction and insulation. For convenience it therefore is referred to hereinafter as a high voltage switching means, even though in the detection position of the switch it may be handling a lower voltage. The apparatus further comprises means controlled by the detection unit 18 to energize an alarm 22, or a fuel shut-off valve 24, or both. More specifically, the detection unit 18 operates a relay 26, which in turn controls the alarm 22 and valve 24.

, Considered in greater detail, there is a low voltage switch M81, preferably a precision switch or so-called microswitch, which is connected in the primary circuit of the step-up transformer 16, and another low voltage switch M82, again preferably a microswitch, which is disposed in the circuit of the valve 24, the latter being electrically operated as by using a solenoid operated valve. In accordance with the present invention, the switches 20, M81, and M82 all form a single control means which may be manually operated between a start position, and a run position, it being understood that the control means, when in the start position, causes switch M81 to energize the source 16, and causes the switch M82 to open the fuel supply valve 24, while switch 20 connects the electrode 14- to the high voltage source 16. When the control means is moved to the run position the switch MCI deenergizes the source 16; the switch 20 connects the electrode 14 to the flame detection means 18; and the switch M82 makes the detection means 13 capable of energizing the alarm 22 or/and shutting the solenoid valve 24 in the event of flame failure.

. Reference is now made to FIGS. 7 through 10 of the drawing, which show one structural form of control means.

The high voltage switch 20 is best shown in FIG. 10, and may be one deck of a multiple deck switch. This deck is indicated in simplified form at 20 in FIG. 8. Its rotor is moved manually by a handle 3ft (FIG. 7) on shaft 32 (FIGS. 8 and 10). The low voltage switches are shown at M81 and M82 in FIG. 9, and they are operated by a cam 34, also mounted on shaft 32. A switch of this type with multiple decks may be used for control of multiple burners, as is later described.

The particular high voltage switch here shown comprises plates 36 and 38 (FIG. 8) spaced apart by spacers 40, and between which plates there is usually a detent means. I remove the detent means and substitute a suitable return spring 42 provided to normally put the control in the run position. in the present case the switch has only two positions, and there are stop or limit means to locate those two positions about 90 apart. The deck 20 is a ring of ceramic or other suitable insulation located between spacers 44 and 46. Without additional decks there would next be an end plate 48. My control device includes still another end plate separated from plate 48 by spacers 52. The parts are all held together by through rods indicated at 54 in FIG. 10. The low voltage microswitches are mounted between the plates 48 and 50, on plate 56. These switches have cam follower rollers indicated at 56 in FIG. 9, for engaging the cam 34.

Referring now to FIG. 10, the shaft 32 carries a rotor or switch arm 58. Electrical connection to arm 58 is made through a spring contact 6% engaging a slip ring or hub 62. The arm 58 engages either of the stationary contacts 64 and 66. The shorter contact 64- is engaged when the control is in start position, that is, it leads to the transformer, and the longer contact as is engaged when the control is in the run position, that is,

4 it leads to the flame monitor circuitry. It will be noted that the contact 66 is longer than the contact 64, which provides extra time for the fiame detector to build up power to hold its relay, as is later described.

Reverting now to FiG. l, the switch 20 corresponds to the ceramic deck of the control assembly, and switches M81 and M82 are actuated by the cam, so that all of the switches operate in response to movement of the single control handle.

Ordinarily cycle A.C. current is supplied on lines L1 and L2, and is controlled by a line switch 70. In operation the line switch 70 is first closed, energizing unit 18 through conductors as and 71, and the operator then may wait a brief interval to see if the alarm 22 is energized, as it should be for lack of flame, it being kept in mind that when the burner was last shut down, that was done by opening the line switch 70, thus leaving the control unit in the run position. As soon as the alarm operates (sound or light or both), showing that the flame detection circuitry is in proper working order, the operator swings the manual control handle from run to start position, whereupon the secondary of the transformer 16 is connected to the electrode 14 of the burner, and simultaneously, or more preferably an instant later, the primary of transformer 16 is energized by closing of the lower contacts of microswitch M81. The second low voltage switch M82 is also closed, thereby energizing the solenoid valve 24 to open the same. The burner is then lighted.

After a suitable interval to permit lighting of the burner, the operator swings the control from the start to the run position. This opens the switch M81 thereby de-energizing transformer 16. Switch 26 disconnects the electrode 14 from transformer 16 and connects it to the flame detection unit 18. If flame is present, as it should be, the relay 26 is actuated to close the normally open lower contacts, thereby maintaining the desired energization of solenoid valve 24 so that it remains open. The upper contacts are opened, de-energizing the alarm 22. Switch M82 is opened so that the solenoid valve 24 is no longer energized through switch M82, and instead its energization will depend on the relay 26. In the event of flame failure the relay 26 is de-energized, thereby closing valve 24 and energizing the alarm 22. Note that the apparatus will fail safe. The arrangement shown in FIG. 2 is partially similar to that shown in FIG. 1, but there is added a tinier or time delay relay 72, and a third low voltage switch or microswitch M83. Other parts are the same as before and are similarly numbered. The switch M83 controls the operation of timer '72, and the contacts of the timer are interposed between the lower contacts of switch M82 and line L2 Referring now to FIG. 9, the third switch is shown at M83, and is similarly provided with a cam follower roller 56 operated by another part of the cam 34. In FIG. 9 the cam is shown in the run position. For the start" 7 position the cam may be visualized as having been turned counterclockwise from the position shown in FIG. 9. In that position the roller of switch M81 will move into cam drop 440; the roller of switch M82 will move into cam drop 442; and the roller of switch M83 will move into cam drop 444. The special shape of cam drop 440 provides a rapid cam rise and quicker changeover for switch M81 than for switches M82 and M83. This provides rapid de-energization of the high voltage transformer and avoids arcing at the contacts of the high voltage switch as the dual-purpose electrode is being switched from the transformer to the flame monitor circuit. It also prevents arcing when starting.

Reverting to FIG. 2, the operation is as follows. The line switch 70 is first closed. At this time the control is still in run position, and switch M83 is closed and supplies power to timer 72. so that its contacts are also closed. After suitable delay, say 45 seconds, this sup- 1! plies power to switch M82. To check, the flame detection and alarm system the control may be left in the run position, as previously described for FIG. 1. The handle is then swung to the start" position, whereupon the electrode 12 is connected to the secondary of transformer 1.6 and switch MS1 energizes the primary of transformer 16. Switch M82 energizes solenoid valve 24 to open the same and supply fuel to the burner which then ignites. The operator then swings the control back to the run position. Switch MS1. de-energizes transformer 16. The electrode 12. is switched to the flame detection unit 18 and, if there is flame, as there should be, the valve 2rd remains energized through relay 26 and is held open. The switch MSZ opens so that solenoid valve 24 is no longer energized through switch M52, and thereafter remains open only so long as it is held open through the relay 2:6.

It the main control has mistakenly been held on start, or is not moved back to run within the time delay interval of the timer 72, the contacts of the timer open, keeping in mind that the timer is no longer energized through switch MS3 when the main control is in the start position instead of the run position. The running out of timer 72 cuts oif the power supply to switch MSZ and results in closing of the solenoid valve 24. The alarm 22 is energized through the upper relay contacts. This guards against any possibility of the oper- .ator forgetting to move the control from start to run promptly, or the switch sticking at start. On the other hand, even if he moves it from start to run, if there is no flame the relay 26 will be open, and solenoid valve 24 will close as it should, and the alarm 22 will be energized.

Referring now to FIG. 3, the arrangement is generally like that shown in FIG. 1, there being a high voltage switch 20 and low voltage switches MS1 and MSZ, a line switch 7i), and a flame detection unit 18 controlling a relay 26 which, in turn, controls an alarm 22 and a solenoid operated fuel valve 24. The latter supplies fuel to a burner, which is not here shown, but the grounded metal body of which is symbolized at 73-. The ignition portion of this burner difiers from that previously described in using two electrodes 74 and 76, both of which are insulated from the grounded body 73', and the tips of which are positioned close enough for ignition purposes. With this arrangement the step-up transformer 78 is modified in having a dual secondary St}, or, diflerently expressed, in having a grounded center tap 79. Of course, in practice, the transformer structure may be the same in FIG. 1 and FIG. 3 if the secondary has three leads, and the difference is merely a difference in how the leads are connected. In FIG. 3, one terminal of the secondary is connected to the high voltage switch 20', and from switch Zll to electrode 74, while the other terminal of the secondary is connected to the other electrode '76. It will be evident that for flame detection purposes it is the electrode 74 that is used here, while the electrode 76 is idle. The electrode '74 is suitably spaced from the grouhded body of the burner, and is suitably located in the burner flame, to act as a flame sensing pickup.

The operation of the circuit is the same as that previously described for FIG. 1, and need not be repeated.

The arrangement shown in FIG. 4 is again intended for use with a burner having two insulated electrodes for ignition. It differs from that shown in FIG. 3 in having a timer or time delay relay '72. controlled by a thrid low voltage switch M83, and thus differs from FIG. 3 in the same way that FIG. 2 differs from FlG. l. The operation of the circuitry shown in FIG. 4 is substantially the same as that described in connection with FIG. 2, and similar reference numerals have been applied except for the step-up transformer marked 78 instead of 15, and the flame immersed electrode marked 74 instead of 14. With these changes the description previously given will apply to the arrangement shown in FIG. 4.

Referring now to FIG. 5, the arrangement there shown resembles that in FIGS. 1 and 3 in having a line switch 70, a high voltage switch 20, low voltage switches MS1 and MS2, and a flame detection means 18 controlling an alarm 2?. and a valve 24 through a relay 26. It difiers in that the burner 12, with its electrode 14, is merely a pilot burner providing a pilot flame for igniting a main burner 52. The valve 24 controls the supply of fuel to the pilot l2, and another electrically operated or solenoid operated valve 84 controls the fuel supply to the main burner 82.

As before, the high voltage switch 20 is arranged to connect the pilot electrode .14 to either the high voltage source 16 for ignition, or to the flame detection means 18 during operation of the burner. The same control means also operates the low voltage switches MS1 and M82. The description previously given for FIG. 1 applies in the main to FIG. 5, but with some differences. When the control is moved to start, transformer 16 is energized by switch MS1 and valve 24 is energized and opened by switch M82, but valve 84 is not yet opened. it is desirable to ignite only the pilot, and to later supply the main fuel, in order to prevent backfire or blow-back or explosion. Indeed, it is primarily for this advantage that a pilot is used.

When the control is moved to the run position. the transformer 16 is tie-energized and the valve 24 will close if there is no pilot flame, but with flame present the relay as is operated to close its normally open contacts as, and thus to supply current through lead 37 to the solenoid of valve 24 to hold the valve open. At this time, the main valve 84- is also opened and this may be done through separate contacts 88 and lead 90. It is inherent, in this arrangement, that the main valve 84 will not open unless the pilot is lit.

As before, the normally closed contacts 92 of the relay may be connected to an alarm 22. In the event of complete flame failure the alarm 22 is energized and both fuel supply valves 24 and 34 are shut. In the event of failure of the pilot flame 24 alone, the same thing happens. In the event of failure of the main flame, without failure of the pilot flame, the valves are not shut, the system being safe because the pilot flame maintains combustion of the main fuel supply reaching the burner. In a sense it is paradoxical to speak of the possibility of failure of the main flame without failure of the pilot fiame.

Reference may be made to FIG. 12 which shows an important application of the invention, to a radiant gas burner. A large frusto conical pocket 450 in a block 452 of high temperature refractory is heated until radiant. The main gas supply comes through passage 82, which corresponds to the main burner shown in FIGS. 5 and 6. The pilot burner is shown at 12., and has a dualpurpose electrode 14. These correspond to the similarly numbered parts in FIGS. 5 and 6.

One advantage of the present invention is that only a single side opening 454 is needed through the refractory block 452. Prior to the present invention it was necessary to provide one passage for the pilot burner, and another separate passage for the flame sensing pickup. It is difiicult to provide such passages through the refractory block, and there is added complication of extra wiring extending to different points around the block. With a separate pickup, the electrode has had to project directly into the path of the flame. This has exposed the electrode to destructive high temperatures, and in the presence of high-velocity high-temperature combustion gases there is a tendency to bend or curl the electrode, as well as to actually consume the same. With the present improvement the dual-purpose electrode is not subjected to such severe conditions, and often will last for years. i

The operation of the circuitry in FIG. 5 may be summarized as follows. The line switch '70 is closed. If the operator waits he can check whether the flame detection unit is in working order, because the alarm will sound or smite light, it being kept in mind that the control switch is in run" position. The operator next moves the control switch to start position, whereupon transformer 16 is energized through switch M51, and the transformer secondary is connected to the gas pilot electrode 14 through switch 20, and pilot fuel is supplied by opening of pilot valve 24, the latter being energized through switch M52. The operator then turns the control means from start to run, whereupon switch MS1 opens, thus de-energizing transformer 16. If flame is present, as it should be, the relay 26 is operated, and valve 24 remains open through relay contacts 86 instead of through the switch MS2. At the same time, if flame is present, contacts 88 of relay 26 close and thereby open main valve 84, and the main flame is ignited by the pilot flame.

The arrangement shown in FIG. 6 is generally like that shown in FIG. in being applied to a pilot burner 12 and a main burner 82. It differs in having a timer or time delay relay 72 controlled by a third low voltage switch M53. Thus the arrangement of FIG. 6 differs from that shown in FIG. 5 in the same way that FIGS. 2 and 4 differ from FIGS. 1 and 3 respectively. The operation of the apparatus shown in FIG. 6 is substantially the same as that described for FIG. 2 except that references to ignition of the burner are applicable to the pilot burner rather than the main burner. The description of FIG. 5 is applicable in that the pilot valve 24, but not the main valve 84, is opened in the start position. The main valve 84 is opened in the run position, and then only in the event that the flame monitor means 18 is satisfied by the presence of a pilot flame.

The operation of the circuit shown in FIG. 6 may be summarized as follows. The line switch 70 is closed, and timer 72 is started through switch M83. After suitable delay, say 45 seconds, the timer runs out and puts power on switch M82. This checks the monitor. The operator moves the main control from run to start" whereupon transformer 16 is energized through switch M51, and the secondary of the transformer is connected to the pilot electrode 14 through high voltage switch 26. The pilot fuel valve 24 is energized through switch MSZ so that a pilot flame is lighted. The control is then swung back from start to run. If this is not done within the time delay of the timer 72, the timer contacts open and fuel valve 24 is closed. Ordinarily, however, the control is swung from start to run within the time delay of timer 72, and in such case transformer 16 is deenergized by opening of switch MSI. Timer '72 is deenergized by opening of switch M81, and pilot valve 24 would be de-energized by opening of switch M82, but meanwhile is energized because of closing of the upper left contacts of relay 26. This, of course, assumes the presence of a pilot flame, but in the absence of such a flame, the pilot valve 24 is shut, and main valve 84 never opens.

As so far described, only a single burner is being controlled, and referring to FIG. 8, the high voltage switch need have only one deck 20. However, in many industrial applications, a bank of burners may be used, and in such case the system may be modified as shown in FIG. 13. In FIG. 13 the power supply line is shown at L1-L2. The low voltage switches are shown at M51, M52, and M83, and the high voltage switches at 20, 120 and 220. These are all operated in unison, as is indicated in FIG. 8 by the provision of the decks 20, 120 and 226. A timer 72 is employed, and the burners are here assumed to have pilots, so that the arrangement is most nearly the same as that shown in FIG. 6.

The rotor of high voltage switch 20 is connected to the electrode 14 of pilot 12; the rotor of high voltage switch 120 is connected to the electrode 114 of pilot 112, and the rotor of high voltage switch 220 is connected to the electrode 214 of pilot 212. Fuel supplied to the pilot burners is controlled by solenoid valves here symbolized at 24, 124 and 224. The main fuel supply for the main 8 burner (not shown) is controlled by solenoid operated valves here marked 84, 184, and 284.

The high voltage source or step-up transformer 16, is sequentially connected to the various burners through a distributor 94 driven by a motor 96 which is energized whenever transformer 16 is energized. The distributor contacts are connected to the high voltage switches 20, 120 and 220, and it will be understood that many more burners may be controlled by extending the circuit shown indefinitely toward the left as viewed in FIG. 13, and adding decks to the high voltage switch, and using more of the distributor contacts. The third connection of high voltage switches 20, 120 and 220 are shown leading to the terminal of flame detection units here indicated by rectangles 18, 118 and 218 respectively, within larger rectangles 18', 118 and 218. It will be seen that there is a flame detection unit for each burner, so that the failure of any burner may be used to shut down the fuel supply of the particular burner, without shutting down the fuel supply to the others. The corresponding alarm 22, 122, or 222 also will indicate which burner has shut down.

The particular flame detection units shown in FIG. 13 are Flame-otrol Model 1470 made by Wheelco Instruments, Division of Barber-Colman Company of Rockford, Illinois.

The units as sold correspond to the large rectangles including relay contacts F and safe start contacts as described later.

The circuitry generally resembles that shown in FIG. 6 but is more advanced in that there is safety programming involving the safe start or purge relay contacts marked SS. A time delay element marked TD controls the SS contacts and functions as a purge timer for safety against residual fuel left in a burner when shut down because of flame failure. Some of the relay contacts F replace some in the relay 26 of FIG. 6, but because of insufficient contacts in the Wheelco unit 18, additional pilot holding relays 27, 127, 227 are used to supplement the contacts F. There are four contacts F, two of which are normally open and two normally closed.

The operation of the arrangement shown in FIG. 13 may be summarized as follows: The line switch '70 is closed whereupon power is supplied through lines L1 and L2 to the terminals L1, L2 within large rectangle 18, and thence to the flame monitoring circuitry in small rectangle 18 to warm the same up and make it operative. Power is also applied from line L1 to terminals 1, 8, and 12. Power applied to terminal 12 goes to a normally closed flame relay contact 440 leading to terminal 2 and thence through conductor 444 and terminal 14 to the time delay element TD, which in this particular case is a bi-metallic or thermal element. The circuit is completed from TD to terminal L2. After a suitable delay for thermal time delay element TD to heat up, its contacts close, and provide power to the safe start relay coil 446, which closes all three of the safe start contacts SS.

The extra time delay here provided for safe start is not needed for a normal start with the burners empty of fuel, but it fulfills a useful function in the event of shutdown during operation when a burner may have residual fuel present. Once the safe start contacts have closed, they are self-holding through the closing of the normally open contacts F.

It will be recalled in connection with FIG. 6 that closing of the line switch 70 applied power to the microswitch M53 and through it to the timer 72. In the present circuit of FIG. 13, switch M83 does not apply power to the timer 72 until all of the safe start contacts have been satisfied or closed, and for this purpose the safe start contacts of the units 1-8, 118 and 218 are connected in series, so that timer '72 will not start until the flame monitor units of all of the burners have been warmed up. More specifically, a circuit starts at line L1 to contact 8 of unit 18', thence through safe start contacts 448 to terminal 7,

and in such case a double pole high voltage relay is used for two burners.

In FIG. 14 a high voltage relay coil 700 controls contacts 520 corresponding to switch 20, and contacts 620 corresponding to switch 120. It will be understood that when the upper contacts are open, the lower contacts are closed, and vice versa, and the center connection of switch 520 leads to the electrode 14 of pilot burner 12, all as previously described for earlier figures of the drawing. The upper contact leads to the high voltage secondary of transformer 516, while the lower contact leads through conductor 490 to contact E of unit 18 for flame monitoring.

Similarly, the center conductor of the high voltage switch 620 leads through conductor 492 to the dual-electrode of pilot burner 112. When the upper contacts of switch 620 are closed, the connection is to the secondary of transformer 516. When the lower contacts are closed, the upper contacts open, and connection is made through conductor 4% to the terminal E of flame monitoring unit 118'.

To start operation, line switch 70 is closed. The ensuing events are the same as previously described for FIG. 13, including time for warm up within the flame detector units, and subsequent running out of timer 72, with consequent lighting of indicator lamp 458, at which time the alarms should sound. The operator then moves the manual control from its normal run position to start position, which closes switch M51. In FIG. 13 the closing of switch MSl energized the high voltage transformer, and the manual movement also shifted the high voltage switches at the ceramic decks. In present FIG. 14 the closing of switch M81 energizes relay coil 700 through conductor 496. It could simultaneously energize transformer 516 by a direct connection to the primary, but as a refinement it is preferred to minimize arcing by delaying the energization of transformer 516 until after changeover of the high voltage contacts. Accordingly, additional low voltage contacts 702 are provided in the relay and are operated by the relay coil 780. These low voltage contacts are so arranged structurally that they close later than the high voltage contacts. Except for this slight delay, the closing of switch M51 is what connects the burner electrode to the high voltage transformer, and energizes the transformer. Meanwhile, micro-switch MSZ causes opening of the pilot fuel valves 24 and 324, as previously described in connection with FIG. l3, and thus the pilot burners ignite.

Within the time delay of the timer 72 the operator releases the manual control to return to its normal run position. This opens micro-switch MSl, thereby deenergizing relay coil 7% and so shifting the burner electrodes from the transformer 516 to the fiame monitoring units 18 and 118'. Meanwhile, because of the structural feature previously mentioned, the low voltage contacts 702 preferably open before the high voltage contacts, thus cutting off high voltage and eliminating arcing when the high voltage contacts open. The remaining operations of the circuitry are the same as previously described in FIG. 13.

In FIG. 14 the high voltage contacts 720 correspond to the high voltage switch 220, and the high voltage contacts 820 take care of the fourth burner 312 (not shown), the flame of which is monitored by the unit 313. The third and fourth burners are ignited by high voltage transformer 616, and the electrodes are switched by the double pole high voltage relay, the coil of which is indicated at 8%. it will be noted that the conductor 496 leading from switch MSl to high voltage relay coil 700 is extended by conductor 498 to the high voltage relay coil 800. Thus, both high voltage relays are operated in unison from the remote manual control.

It will be understood that fifth and sixth burners would form an additional pair for which another localized high .voltage transformer and high voltage relay may beprovided, these'also being controlled from switch M81, as previously described, by a further extension of conductor 496, 498.

It is believed that the construction, operation and meth- 0d of use of my improved apparatus, as well as the advantages thereof, will be apparent from the foregoing detailed description. A dual purpose electrode is used both for ignition and for flame detection. This electrode is relatively sheltered and long lived. The apparatus may be used to simultaneously control an entire bank of burners, and if desired, this may be done by low voltage wiring, with high voltage wiring localized at the burners.

It will be understood that while I have shown and described my invention in several preferred forms, changes may be made in the structures and circuitry shown, without departing from the scope of the invention as sought to be defined in the following claims. In the claims the term switch is intended to include relay contacts acting as a switch.

I claim:

1. Apparatus for burner ignition and flame detection, comprising a low voltage source and a fuel burner having an electrode positioned to be in the burner flame and near another conductive part of the system, ignition means including a high voltage source adapted to adjust an ignition spark from said electrode, said high voltage source providing a potential of the order of 10,000 volts, a flame detection unit of the type responsive to an electrode immersed in flame, a circuit for energizing said flame detection unit from said low voltage source, a high voltage switching means, and circuit means adapted to so connect said electrode, said high voltage source, and said flame detection unit with said switching means that said switching means may be used to connect said electrode to either the high voltage source for starting the burner by spark ignition or to said detection unit during running of the burner.

2. Apparatus for burner ignition and flame detection, comprising a low voltage source and a fuel burner having an electrode positioned to be in the burner flame and near another conductive part of the system, ignition means including a high voltage source adapted to cause an ignition spark from said electrode, said high voltage source providing a potential of the order of 10,000 volts, a flame detection unit of a type responsive to an electrode immersed in flame, a circuit for energizing said flame detection unit from said low voltage source, a high voltage switching means, circuit means adapted to so connect said electrode, said high voltage source, and said flame detection unit with said switching means that said switching means may be used to connect said electrode to either the high voltage source for starting the burner by spark ignition or to said detection unit during running of the burner, and means controlled by said detection unit to energize an alarm and a fuel shut-off valve leading to the burner.

3. Apparatus for burner ignition and flame detection, comprising a low voltage source and a fuel burner having an electrode positioned to be in the burner flame near another conductive part of the system, ignition means including a high voltage source and an energizing supply for said source, adapted to cause an ignition spark from said electrode, a flame detection unit of a type responsive to an electrode immersed in flame, a circuit for energizing said flame detection unit from said low voltage source, a high voltage switching means, circuit means adapted to so connect said electrode, said high voltage source, and said flame detection unit with said switching means that said switching means may be used to connect said electrode in start position to the high voltage source for starting the burner or in run position to said detection unit during running of the burner, a solenoid operated valve in the fuel supply, a low voltage switch connected in the energizing supply for said high voltage source, a second low voltage switch disposed in the v 13 solenoid valve circuit, and a single control means to operate said high and low voltage switches, the control means when in start position causing said first low voltage switch to energize the high voltage source, and said second low voltage switch to open the fuel supply valve, and said control means in run position causing said first low voltage switch to de-energize the high volt- 'agesource, and causing said second low voltage switch to make the detection means capable of energizing an alarm and of shutting the solenoid valve in the event of flame failure. I 4. Apparatus for burner ignition and flame detection, comprising a low voltage source and a fuel burner havm'g an electrode positioned to be in the burner flame hear another conductive part of the system, ignition means including a step up transformer adapted to cause an ignition spark from said electrode, a flame detection unit of a type responsive to an electrode immersed in flame, a. circuit for energizing said flame detection unit from said low voltage source, a high voltage switching means, circuit means adapted to so connect said electrode, said transformer, and said flame detection unit with said switching means that said switching means may be used toc'onnect said electrode in start position to the transformer for starting the burner 61' in run position to said detection unit during running of the burner, a solenoid operated valve in the fuel supply, a relay having a coil and a switch operated thereby in said valve circuit, said being responsive to said detection unit, a low voltage switch having contacts connected in the transformer primary circuit, a second low voltage switch having contacts disposed in the valve circuit in shunt with the switch of said relay, and a single manually operable means to operate said high and low voltage switches, the control means when in start position causing said first low voltage switch to energize the transformer and said second low voltage switch to open the fuel supply valve, said control means when in run position causing said first low voltage'switch to de-energize the transformer, and causing said second low voltage switch to cease its opening of the fuel valve, whereby the latter then kept open by the aforesaid relay during the continuance of flame and is shut in the event of flame failure. 5. Apparatus for. burner ignition and flame detection,

comprising a low voltage source and a fuel burner having electrode positioned to be in the burner flame near another conductive partof the system, ignition means including a high voltage source and an energizing supply for said source adapted to cause an ignition spark from said electrode, a fianaedetection unit of a type responsive to an electrode immersed in flame, a high voltage switching means, a circuit for energizing said flame detection unit from said lowvoltage source, circuit means adapted to so connect said electrode, said high voltage source, and 7 said flame detection unit with said switching means that said switching means may be used to connect said electrode in start position to the high voltage source for starting the burner or in run position to said detection unit during of the burner, a solenoid operated valve in the fuel supply, a low voltage switch connected in the energizing supply for said high voltage source, a second low voltage switch disposed in the solenoid valve circuit, a timer having a switch operator and a switch the contacts of which are connected in the circuit ofsaid second low voltage switch, a third low Voltage switch ancl an electrical circuit controlled thereby for controlling the operation of the operator of said timer,

and a single control means to operate said high and low voltage switches, the control means when in start position causing said first low voltage switch to energize the high voltage source, and said second low voltage switch to open the fuel supply valve, and said third low voltage switch to start the operator of the timer, and said control means when in run position causing said first low voltage switch to de-energize the source and causing 14 said'second low voltage switch to make the detectidii means capable of energizing an alarm and of shutting the solenoid valve in the event of flame failure after running out of the timer. 7

6. Apparatus for burner ignition and flame detectioh, comprising a low voltage source and a fuel burner having an electrode positioned to be in the burner flame near another conductive part of the system, ignition means including a step up transformer adapted to 6311186 an ignition spark nom said electrode, a flame detection unit of a type responsive to an electrode immersed in flame, a circuit for energizing said flame detection unit from said low voltage source, a high voltage switching means, circuit means adapted to so connect said electrode, said transformer, and said flame detection unit with said switching means that said switching means may be used to connect said electrode in start position to the transformer for st arting the burner or in run position to said detection unit during running of the burner, a solenoid operated valve in the fuel supply, a relay having a coil and a switch operated thereby in said valve circuit, said coil being responsive to said detection unit, a low voltage switchhaving contacts connected in the transformer primary circuit, a second low voltage switch having contacts disposedin the valve circuit in shunt with the relay, a timer having a switch operator and a switch the contacts of which are connected in the circuit of said second low voltage switch, a third low voltage switch and an electrical circuit controlled thereby for controlling the operation of the operator of said timer, and a single manually operable control means to operate said high and low voltage switches, the control means when in start position causing said first low voltage switch to energize the transformer, and said second low voltage switch to open the fuel supply valve, and said third low voltage switch to start the operator of the timer, and said control means when in run position causing said first low voltage switch to de-energize the transformer and causing said second low voltage switch to cease its opening of the fuel valve, whereby the latter then is kept open by the aforesaid relay during the continuance of flame but is shut in the event of flame failure after running out of the timer.

7. Apparatus for burner ignition and flame detection as defined in claim 1, in combination with a main fuel burner anda pilot burner, and in which the electrode rod passes through and structurally forms a part of the pilot burner.

8. Apparatus for burner ignition and flame detection as defined in claim '3, in combination with a main fuel burner and a pilot burner, and in which the electrode rod passes through and structurally forms a part of the pilot burner, and in which there are two solenoid operated valves, one of which controls the fuel supply to the main burner, and the other of which controls the fuel supply to the pilot burner, and in which the detection means serves to shut both solenoid valves in the event of flame failure.

9. Apparatus for burner ignition and flame detection as deflned'in claim '5, in combination with a main fuel burner and a pilot burner, and in which the electrode rod passes through and structurally forms a part of the pilot burner, and in which there are two solenoid operated valves, one of which controls the fuel supply to the main burner, and the other of which controls the fuel supply to the pilot burner, and in which the detection means serves to shut both solenoid valves in the event of flame failure.

'10. Apparatus for burner ignition and flame detection as defined in claim 2, in combination with a main fuel burner and a pilot burner, and in which there is only one electrode rod which passes through and structurally forms a part ofthe pilot burner, and in which there are two'solenoid operated valves, one of which controls the 15 fuel supply to the main burner, and the other of which controls the fuel supply to the pilot burner, and in which only the latter is opened in start position, and in which the detection means serves to shut both solenoid valves in the event of flame failure.

11. Apparatus for burner ignition and flame detection as defined in claim 4, in combination with a main fuel burner and a pilot burner, and in which there is only one electrode rod which passes through and structurally forms a part of the pilot burner, and in which there are two solenoid operated valves, one of which controls the fuel supply to the main burner, and the other of which controls the fuel supply to the pilot burner, and in which only the latter is opened in start position, and in which the detection means serves to shut both solenoid valves in the event of flame failure.

12. Apparatus for burner ignition and flame detection as defined in claim 6, in combination with a main fuel burner and a pilot burner, and in which there is only one electrode rod which passes through and structurally forms a part of the pilot burner, and in which there are two solenoid operated valves, one of which controls the fuel supply to the main burner, and the other of which controls the fuel supply to the pilot burner, and in which only the latter is opened in start position, and in which the detection means serves to shut both solenoid valves in the event of flame failure.

13. Apparatus for burner ignition and flame detection as defined in claim 3, in combination with a plurality of burners, each having its own electrode and flame detection unit and solenoid operated fuel valve, and in which there is a high voltage switch for each burner but the first and second low voltage switches operate circuit means which function in common for all of the burners, and in which the single control means operates the low voltage switches and all of the high voltage switches.

14. Apparatus for burner ignition and flame detection as defined in claim 4, in combination with a plurality of burners, each having its own electrode and flame detection unit and relay and solenoid operated fuel valve, and in which there is a high voltage switch for each burner but the first, second, and third low voltage switches operate circuit means which function in common fortall of the burners, and in which the single manually operable control means operates the low voltage switches and all of the high voltage switches.

15. Apparatus for burner ignition and flame detection as defined in claim 5, in combination with a plurality of burners, each having its own electrode and flame detection unit and relay and solenoid operated fuel valve, and in which there is a high voltage switch for each burner but the first and second low voltage switches and timer operate circuit means which function in common for all of the burners, and in which the single control means operates the low voltage switches and all of the high voltage switches.

16. Apparatus for burner ignition and flame detection as defined in claim 6, in combination with a plurality of burners, each having its own electrode and flame detection unit, and relay and solenoid operated fuel valve, and in which there is a high voltage switch for each burner but the first, second, and third low voltage switches and timer operate circuit means which function in common for all of the burners, and in which the single manually operable control means operates the low voltage switches and all of the high voltage switches.

17. Apparatus for burner ignition and flame detection as defined in claim 3, in combination with a plurality of burners, each having its own electrode and flame detection unit and solenoid operated fuel valve, and in which there is a high voltage switch for each burner but the first and second low voltage switches operate circuit means which function in common for all of the burners, and in which the high voltage switches constitute a multiple deck unit with a single shaft and with a deck for each burner, and

16 in which the single control means operates the low voltage switches and all of the high voltage switches, and in which the high voltage source is combined with a rotary motor driven distributor for connection rapidly sequentially to the dilferent burners through the said high voltage switches.

18. Apparatus for burner ignition and flame detection as defined in claim 4, in combination with a plurality of burners, each having its own electrode and flame detection unit and relay and solenoid operated fuel valve, and in which there is a high voltage switch for each burner but the first, second, and third low voltage switches operate circuit means which function in common for all of the burners, and in which the high volt-age switches constitute a multiple deck unit with a single shaft and with a deck for each burner, and in which the single manually operable control means operates the low voltage switches and all of the high voltage switches, and in which the high voltage source is combined with a rotary motor driven distributor for connection rapidly sequentially to the dilferent burners through the said high voltage switches.

19. Apparatus for burner ignition and flame detection as defined in claim 5, in combination with a plurality of burners, each having its own electrode and flame detection unit and relay and solenoid operated fuel valve, and in which there is a high voltage switch for each burner but the first and second low voltage switches and timer operate circuit means which function in common for all of the burners, and in which the high voltage switches constitute a multiple deck unit with a single shaft and with a deck for each burner, and in which the single control means operates the low voltage switches and all of the high voltage switches, and in which the high voltage source is combined with a rotary motor driven distributor for connection rapidly sequentially to the different burners through the said high voltage switches.

20. Apparatus for burner ignition and flame detection as defined in claim 6, in combination with a plurality of burners, each having its own electrode and flame detection unit and relay and solenoid operated fuel valve, and in which there is a high voltage switch for each burner but the first, second, and third low voltage switches and timer operate circuit means which function in common for all of the burners, and in which the high voltage switches constitute a multiple deck unit with a single shaft and with a deck for each burner, and in which the single manually operable control means operates the low voltage switches and all of the high voltage switches, and in which the high voltage source is combined with a rotary motor driven distributor for connection rapidly sequentially to the different burners through the said high voltage switches.

21. Apparatus for burner ignition and flame detection as defined in claim 3, in combination with a plurality of burners, each having its own electrode and flame detection unit and solenoid operated fuel valve, and in which there are a plurality of relay-type high voltage switches for the burners, said switches each comprising a low voltage coil and a high voltage switch operated thereby, said relay-type high voltage switches being 10- calized at the burners, but in which the first and second low voltage switches operate circuit means which function in common for all of the burners, and in which the single manually operable control means operates the low voltage switches directly and operates the coils of the relay-type high voltage switches indirectly through low voltage wiring leading from the control means to the relay-type high voltage switches, and in which there are a plurality of high voltage sources localized at the relaytype high voltage switches and burners.

22. Apparatus for burner ignition and flame detection as defined in claim 4, in combination with a plurality of burners, each having its own electrode and flame detection unit and relay and solenoid operated fuel valve, and in which there are a plurality of relay-type high voltage 17 switches for the burners, said switches each comprising a low voltage coil and a high voltage switch operated thereby, said relay-type high voltage switches being localized at the burners, but in which the first and second low voltage switches operate circuit means which function in common for all of the burners, and in which the single manually operable control means operates the low voltage switches directly and operates the coils of the relaytype high voltage switches indirectly through low voltage wiring leading from the control means to the relay-type high voltage switches, and in which there are a plurality of high voltage sources localized at the relay-type high voltage switches and burners.

23. Apparatus for burner ignition and flame detection as defined in claim 5, in combination with a plurality of burners, each having its own electrode and flame detection unit and solenoid operated fuel valve, and in which there are a plurality of relay-type high voltage switches for the burners, said switches each comprising a low voltage coil and a high voltage switch operated thereby, said relay-type high voltage switches being 10- calized at the burners, but in which the first, second and third low voltage switches and the timer operate circuit means which function in common for all of the burners, and in which the single manually operable control means operates the low voltage switches directly and operates the coils of the relay-type high voltage switches indirectly through low voltage wiring leading from the control means to the relay-type high voltage switches, and in which there are a plurality of high voltage sources localized at the relay-type high voltage switches and burners.

24. Apparatus for burner ignition and flame detection as defined in claim 6, in combination with a plurality of burners, each having its own electrode and flame detection unit and relay and solenoid operated fuel valve, and in which there are a plurality of relay-type high voltage switches for the burners, said switches each comprising a low voltage coil and a high voltage switch operated thereby, said relay-type high voltage switches being localized at the burners, but in which the first, sec ond and third low voltageswitches and the timer operate circuit means which function in common for all of the burners, and in which the single manually operable control means operates the low voltage switches directly and operates the coils of the relay-type high voltage switches indirectly through low voltage wiring leading from the control means to the relay-type high voltage switches, and in which there are a plurality of high voltage sources localized at the relay-type high voltage switches and burners.

References Cited in the file of this patent UNITED STATES PATENTS 2,152,790 Clark Apr. 4, 1939 2,238,890 Clark Apr. 22, 1941 2,304,200 Plein et a1. Dec. 8, 1942 2,539,208 Schultz et al. Ian. 23, 1951 2,627,308 Clark Feb. 3, 1953 

